Like the aHUS, infections andother stressors can trigger TTP, but in aHUS the ADAMTS13 levels are normal.13 PF can also trigger hemolytic anemia orother forms of anemia.14,15 leading to the combination of tissueextravasation, external losses, and microangiopathic hemolysis, which are thecharacteristics of the disease.15 The gene discussed is ADAMTS13; the disease is thrombotic thrombocytopenic purpura.